SHIFTING OF COASTLINE AND EVOLUTION OF TIDAL FLAT IN MODERN YELLOW RIVER DELTA

Based on TM images and depth data accumulated in the past years,using such technology as GIS and RS,we studied the changes of Coastal Wetland in the Yellow River delta.It was revealed that the coastline was progressed in the estuary,retreated in the north coast by erosion of the abandoned delta,and remained stable in the south of the Laizhou Bay since the River took the course of the Qingshuigou channel to the sea in 1976.In the early stage after the shifting of main channel,the tidal flat grew rapidly.And during the period of 1976—1987,the tidal flat was expanded in a circle like around the river mouth.The area of tidal flat was slightly reduced during 1981—1987 due to agricultural cultivation and oil development.The Yellow River changed its course again in 1996.The new river mouth was rapidly silting up,the area of tidal flat grew slightly near the river mouth in 1998,whereas the old river mouth was under intensified erosion.As the result,the tidal flat of the Yellow River has been in an overall status of reducing since then.